In general, water purifiers are classified into an air collection type water purifier used by collecting moisture from the air, a faucet direct-connection type water purifier connected to a waterworks pipe, and a spring water supply type water purifier used by directly supplying purified water thereto. Such purifiers are selectively used depending on conditions of a place and require continuous maintenance so that a user drinks sanitized water in contaminated environment.
A method of periodically cleaning the interior of a water purifier or circulating water is used to solve such a problem. In case of a cold/hot water purifier, its interior is cleaned by cleansing only the interiors of a storage tank for supplying cold/hot water and cold/hot water supply tanks or by periodically replacing filters. However, since only the cleansing of the interiors of the storage tank and the cold/hot water supply tanks and the replacement of filters are performed, problems for sanitary reasons with respect to connection pipes and other parts in the water purifier still remain.
Therefore, although the cleansing of the interiors of the storage tank and the cold/hot water supply tanks is finished, water inside the water purifier is again circulated along the connection pipes, and pollutants are flowed into the interiors of the storage tank and the cold/hot water supply tanks. Accordingly, the water is exposed to the pollutants as it is. Further, although the filters are periodically replaced, the pollutants are not removed without cleansing or replacing a connection pipe to the storage tank in which water is stored from the filters and other connection pipes. Furthermore, problems of cost and maintenance are proposed to solve them.
In addition, if a certain time (three hours) elapses in the state that clean water does not flow but remain inside the water purifier, bacteria (hereinafter, referred to as “microbes”) harmful to human bodies are reproduced, and the number of microbes increases by geometric progression.
That is, in case of the faucet direct-connection type water purifier, a chloride contents are added into tap water initially supplied to the interior of the water purifier so that microbes are not produced. However, while the tap water passes through the filters of the water purifier, the chloride contents are filtered and purified. Therefore, if the purified water is not flowed but left for a certain period of time, the number of microbes exceeds a permissible level while the microbes are reproduced. Further, if water does not flow but remain in the filters for a certain period of time, biofilm is formed in a filter film. Particularly, at night when the water purifier is less used, the number of microbes increases by geometric progression after a certain period of time elapses. Therefore, the filters mainly cause pollution of the water purifier.
The pollution of the water purifier results in a problem for sanitary reasons. A method of circulating water is proposed to solve such a problem. However, a water level sensor is placed in a water tank in which water is temporarily stored. Here, the water level sensor senses a level of water and allows water to be circulated when the level of water reaches a predetermined level. Accordingly, the water tank and the water level sensor are additionally installed in the water purifier.
However, it is difficult that a water level sensor is normally operated due to vibrations of water at a place such as a vessel, and an overload is applied to a circulation pump for circulating water due to malfunction of the sensor. Further, since an installation space of the water tank is additionally provided, space utilization is lowered.
In the conventional water purifier, a fundamental solution is required in providing optimum drinking water.